Use BusyBox in the initrd

Using BusyBox instead of Bash plus a bunch of other tools gives us a
much more feature-full, yet smaller initrd.  In particular, BusyBox
contains networking commands such as ip and a DHCP client, useful for
NFS boots.  It's also much more convenient for rescue situations
because the shell has builtin readline support and there are many more
tools (including vi).

modules/module-list.nix

@@ -196,7 +196,6 @@
   ./system/boot/luksroot.nix
   ./system/boot/modprobe.nix
   ./system/boot/stage-1.nix
-  ./system/boot/stage-1-extratools.nix
   ./system/boot/stage-2.nix
   ./system/etc/etc.nix
   ./system/upstart-events/control-alt-delete.nix

modules/system/boot/stage-1-init.sh

@@ -3,7 +3,7 @@
 targetRoot=/mnt-root
 
 export LD_LIBRARY_PATH=@extraUtils@/lib
-export PATH=@extraUtils@/bin
+export PATH=@extraUtils@/bin:@extraUtils@/sbin
 
 
 fail() {
@@ -50,7 +50,7 @@ EOF
     esac
 }
 
-trap 'fail' ERR
+trap 'fail' 0
 
 
 # Print a greeting.
@@ -60,8 +60,9 @@ echo
 
 
 # Mount special file systems.
-mkdir -p /etc # to shut up mount
-echo -n > /etc/fstab # idem
+mkdir -p /etc
+touch /etc/fstab # to shut up mount
+touch /etc/mtab # to shut up mke2fs
 mkdir -p /proc
 mount -t proc none /proc
 mkdir -p /sys
@@ -120,6 +121,8 @@ done
 
 
 # Load the required kernel modules.
+mkdir -p /lib
+ln -s @modulesClosure@/lib/modules /lib/modules
 echo @extraUtils@/bin/modprobe > /proc/sys/kernel/modprobe
 for i in @kernelModules@; do
     echo "loading module $(basename $i)..."
@@ -259,16 +262,12 @@ mountFS() {
 # Try to find and mount the root device.
 mkdir /mnt-root
 
-mountPoints=(@mountPoints@)
-devices=(@devices@)
-fsTypes=(@fsTypes@)
-optionss=(@optionss@)
+exec 3< @fsInfo@
 
-for ((n = 0; n < ${#mountPoints[*]}; n++)); do
-    mountPoint=${mountPoints[$n]}
-    device=${devices[$n]}
-    fsType=${fsTypes[$n]}
-    options=${optionss[$n]}
+while read -u 3 mountPoint; do
+    read -u 3 device
+    read -u 3 fsType
+    read -u 3 options
 
     # !!! Really quick hack to support bind mounts, i.e., where the
     # "device" should be taken relative to /mnt-root, not /.  Assume
@@ -300,7 +299,7 @@ for ((n = 0; n < ${#mountPoints[*]}; n++)); do
     # that we don't properly recognise.
     if test -z "$pseudoDevice" -a ! -e $device; then
         echo -n "waiting for device $device to appear..."
-        for ((try = 0; try < 20; try++)); do
+        for try in $(seq 1 20); do
             sleep 1
             if test -e $device; then break; fi
             echo -n "."
@@ -326,7 +325,7 @@ udevadm control --exit || true
 
 # Kill any remaining processes, just to be sure we're not taking any
 # with us into stage 2.
-kill -9 -- -1
+pkill -9 -v 1
 
 
 if test -n "$debug1mounts"; then fail; fi

modules/system/boot/stage-1.nix

@@ -129,7 +129,7 @@ let
   # work.
   extraUtils = pkgs.runCommand "extra-utils"
     { buildInputs = [pkgs.nukeReferences];
-      allowedReferences = [ "out" modulesClosure ]; # prevent accidents like glibc being included in the initrd
+      allowedReferences = [ "out" ]; # prevent accidents like glibc being included in the initrd
       doublePatchelf = (pkgs.stdenv.system == "armv5tel-linux");
     }
     ''
@@ -139,28 +139,21 @@ let
       # Copy what we need from Glibc.
       cp -pv ${pkgs.glibc}/lib/ld*.so.? $out/lib
       cp -pv ${pkgs.glibc}/lib/libc.so.* $out/lib
+      cp -pv ${pkgs.glibc}/lib/libm.so.* $out/lib
       cp -pv ${pkgs.glibc}/lib/libpthread.so.* $out/lib
       cp -pv ${pkgs.glibc}/lib/librt.so.* $out/lib
       cp -pv ${pkgs.glibc}/lib/libdl.so.* $out/lib
       cp -pv ${pkgs.gcc.gcc}/lib*/libgcc_s.so.* $out/lib
 
+      # Copy BusyBox.
+      cp -rvd ${pkgs.busybox}/{bin,sbin} $out/
+      chmod -R u+w $out
+
       # Copy some utillinux stuff.
-      cp -v ${pkgs.utillinux}/bin/mount ${pkgs.utillinux}/bin/umount \
-         ${pkgs.utillinux}/sbin/fsck ${pkgs.utillinux}/sbin/switch_root \
-         ${pkgs.utillinux}/sbin/blkid ${pkgs.utillinux}/bin/setsid $out/bin
+      cp -v ${pkgs.utillinux}/sbin/blkid $out/bin
       cp -pdv ${pkgs.utillinux}/lib/libblkid*.so.* $out/lib
       cp -pdv ${pkgs.utillinux}/lib/libuuid*.so.* $out/lib
-
-      # Copy some coreutils.
-      cp -v ${pkgs.coreutils}/bin/basename $out/bin
-      cp -v ${pkgs.coreutils}/bin/mkdir $out/bin
-      cp -v ${pkgs.coreutils}/bin/mknod $out/bin
-      cp -v ${pkgs.coreutils}/bin/chmod $out/bin
-      cp -v ${pkgs.coreutils}/bin/cat $out/bin
-      cp -v ${pkgs.coreutils}/bin/chroot $out/bin
-      cp -v ${pkgs.coreutils}/bin/sleep $out/bin
-      cp -v ${pkgs.coreutils}/bin/ln $out/bin
-
+      
       # Copy dmsetup and lvm.
       cp -v ${pkgs.lvm2}/sbin/dmsetup $out/bin/dmsetup
       cp -v ${pkgs.lvm2}/sbin/lvm $out/bin/lvm
@@ -174,12 +167,8 @@ let
       cp -v ${pkgs.udev}/lib/udev/*_id $out/bin
       cp -pdv ${pkgs.udev}/lib/libudev.so.* $out/lib
 
-      # Copy bash.
-      cp -v ${pkgs.bash}/bin/bash $out/bin
-      ln -sv bash $out/bin/sh
-
       # Copy modprobe.
-      cp -v ${pkgs.module_init_tools}/sbin/modprobe $out/bin/modprobe.real
+      cp -v ${pkgs.module_init_tools}/sbin/modprobe $out/bin/modprobe
 
       # Maybe copy splashutils.
       ${optionalString enableSplashScreen ''
@@ -188,6 +177,10 @@ let
 
       ${config.boot.initrd.extraUtilsCommands}
 
+      # Strip binaries further than normal.
+      chmod -R u+w $out
+      stripDirs "lib bin" "-s"
+
       # Run patchelf to make the programs refer to the copied libraries.
       for i in $out/bin/* $out/lib/*; do if ! test -L $i; then nuke-refs $i; fi; done
 
@@ -201,27 +194,15 @@ let
           fi
       done
 
-      # Make the modprobe wrapper that sets $MODULE_DIR.
-      cat > $out/bin/modprobe <<EOF
-      #! $out/bin/bash
-      export MODULE_DIR=${modulesClosure}/lib/modules
-      exec $out/bin/modprobe.real "\$@"
-      EOF
-      chmod u+x $out/bin/modprobe
-
       # Make sure that the patchelf'ed binaries still work.
       echo "testing patched programs..."
-      $out/bin/bash --version | grep "bash, version"
+      $out/bin/ash -c 'echo hello world' | grep "hello world"
       export LD_LIBRARY_PATH=$out/lib
-      $out/bin/mount --version | grep "mount from"
-      $out/bin/umount --version | grep "umount "
+      $out/bin/mount --help 2>&1 | grep "BusyBox"
       $out/bin/udevadm --version
-      $out/bin/blkid -v 2>&1 | tee -a $out/log | grep "blkid from util-linux"
       $out/bin/dmsetup --version 2>&1 | tee -a $out/log | grep "version:"
       LVM_SYSTEM_DIR=$out $out/bin/lvm version 2>&1 | tee -a $out/log | grep "LVM"
       $out/bin/mdadm --version
-      $out/bin/basename --version
-      $out/bin/modprobe --version
 
       ${config.boot.initrd.extraUtilsCommandsTest}
     ''; # */
@@ -291,25 +272,20 @@ let
   bootStage1 = pkgs.substituteAll {
     src = ./stage-1-init.sh;
 
-    shell = "${extraUtils}/bin/bash";
+    shell = "${extraUtils}/bin/ash";
 
     isExecutable = true;
 
-    inherit udevConf extraUtils;
+    inherit udevConf extraUtils modulesClosure;
 
     inherit (config.boot) resumeDevice devSize runSize;
 
     inherit (config.boot.initrd) checkJournalingFS
       preLVMCommands postDeviceCommands postMountCommands kernelModules;
 
-    # !!! copy&pasted from upstart-jobs/filesystems.nix.
-    mountPoints =
-      if fileSystems == []
-      then abort "You must specify the fileSystems option!"
-      else map (fs: fs.mountPoint) fileSystems;
-    devices = map (fs: if fs.device != null then fs.device else "/dev/disk/by-label/${fs.label}") fileSystems;
-    fsTypes = map (fs: fs.fsType) fileSystems;
-    optionss = map (fs: fs.options) fileSystems;
+    fsInfo =
+      let f = fs: [ fs.mountPoint (if fs.device != null then fs.device else "/dev/disk/by-label/${fs.label}") fs.fsType fs.options ];
+      in pkgs.writeText "initrd-fsinfo" (concatStringsSep "\n" (concatMap f fileSystems));
   };
 
 

modules/virtualisation/qemu-vm.nix

@@ -252,10 +252,6 @@ in
     ''
       # We need mke2fs in the initrd.
       cp ${pkgs.e2fsprogs}/sbin/mke2fs $out/bin
-
-      # And `ip' (which needs libresolv.so).
-      cp ${pkgs.iproute}/sbin/ip $out/bin
-      cp ${pkgs.glibc}/lib/libresolv.so.* $out/lib
     '';
 
   boot.initrd.postDeviceCommands =